Strawflower(Helichrysum bracteatum)capitula have papery bracts and thus have the qualities of a naturally dried flower.The involucral bract cells have a secondary cell wall(SCW)of which a crucial component is lignin.A...Strawflower(Helichrysum bracteatum)capitula have papery bracts and thus have the qualities of a naturally dried flower.The involucral bract cells have a secondary cell wall(SCW)of which a crucial component is lignin.Although the constituents of SCWs have been studied extensively in plants,little is known of the mechanism regulating SCW formation,especially lignin biosynthesis in the involucral bracts of strawflower.In this study,a homolog of NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1,designated Hb NST1,was identified as a positive regulator of lignin biosynthesis in strawflower.The transcript level of Hb NST1 was the highest in the involucral bracts.Subcellular localization analysis indicated that Hb NST1 was localized to the nucleus.Overexpression of Hb NST1 in Chrysanthemum indicum promoted the expression of a gene related to lignin biosynthesis,a homolog of cinnamyl alcohol dehydrogenase,designated Ci CAD,suggesting that Hb NST1 was associated with the accumulation of lignin in the SCW of the involucral bracts.Taken together,the results suggested that Hb NST1 positively regulated lignin accumulation in the involucral bracts and mediated the expression of lignin biosynthesis-related genes in strawflower.展开更多
基金supported by National Key R&D Program of China(Grant No.2018YFD1000403)The National Natural Science Foundation(Grant Nos.32002072 and 31772347)China Postdoctoral Science Foundation(Grant No.2021M693429)。
文摘Strawflower(Helichrysum bracteatum)capitula have papery bracts and thus have the qualities of a naturally dried flower.The involucral bract cells have a secondary cell wall(SCW)of which a crucial component is lignin.Although the constituents of SCWs have been studied extensively in plants,little is known of the mechanism regulating SCW formation,especially lignin biosynthesis in the involucral bracts of strawflower.In this study,a homolog of NAC SECONDARY WALL THICKENING PROMOTING FACTOR 1,designated Hb NST1,was identified as a positive regulator of lignin biosynthesis in strawflower.The transcript level of Hb NST1 was the highest in the involucral bracts.Subcellular localization analysis indicated that Hb NST1 was localized to the nucleus.Overexpression of Hb NST1 in Chrysanthemum indicum promoted the expression of a gene related to lignin biosynthesis,a homolog of cinnamyl alcohol dehydrogenase,designated Ci CAD,suggesting that Hb NST1 was associated with the accumulation of lignin in the SCW of the involucral bracts.Taken together,the results suggested that Hb NST1 positively regulated lignin accumulation in the involucral bracts and mediated the expression of lignin biosynthesis-related genes in strawflower.
